The present invention relates to switchable electrochromic devices for use in windows for aircraft. More particularly, the present invention is directed to aircraft transparency windows which are anti-fogging and which have variable light transmittance.
The transmission of unwanted sound/vibrations through an aircraft transparency and into the aircraft, in particular the aircraft cabin, is undesirable and can cause discomfort to the cabin""s occupants. Efforts have been made to reduce the transmission of sound/vibrations through aircraft transparencies. Such efforts have been generally directed to transparencies having several panes (e.g. four or more panes) maintained in spaced-apart relationship within a spacer-frame assembly, which spacer frame assembly is affixed to a corresponding opening in the body of the aircraft. The spaced panes provide a plurality of airspaces therebetween, which, among other things, reduce or eliminate the transmission of external sound/vibrations through the transparency into the cabin. Such transparencies may further include an electroconductive layer that can be heated upon application of electrical current thereto, thus providing an anti-fog characteristic to the aircraft window assembly.
Electrochromic devices have been proposed for a number of uses, such as architectural windows and automotive windows and mirrors. Such electrochromic devices typically include a sealed chamber defined by two pieces of glass that are separated by a gap or space that contains an electrochromic medium. The glass substrates typically include transparent conductive layers coated on facing surfaces of the glass and are in contact with the electrochromic medium. The conductive layers on both glass substrates are connected to electronic circuitry that is effective to electrically energize the electrochromic medium and change the color of the medium. For example, when the electrochromic medium is energized, it may darken and begin to absorb light.
Electrochromic devices have most commonly been used in rear-view mirrors for automotive applications. In such uses, a photocell can be incorporated into the electrochromic cell to detect a change in light reflected by the mirror. When a specific level of light is reflected, for instance when lights are reflected at night, the photocell is activated to apply an electrical potential to the electrodes in the cell, thus causing the electrochemical medium to change color and create a darkening affect, thereby dimming the mirror to the lights. Electrochemical devices have also been considered for use in other automotive applications, such as windshields and windows, as well as architectural applications such as building windows.
It has been proposed to add an electrochromic assembly on the inside of a conventional curved outer window. Such an aircraft window adds significant weight to the overall aircraft structure. Moreover, the additional substrates and electrochromic assembly reduce the light transmittance and increase the reflective distortion of the aircraft window.
As can be appreciated, it would be advantageous to provide an aircraft window assembly which provides anti-fogging properties, which reduces or eliminates unwanted sound, which is capable of varying light transmittance, which reduces reflective distortion, and which minimizes additional weight to the aircraft.
The present invention provides an electrochromic aircraft window assembly comprising: a) an outboard pane assembly; and b) a fog preventing electrochromic pane assembly spaced from said outboard pane assembly and defining a chamber therebetween, said fog preventing electrochromic pane assembly comprising: i) a first substrate having a first surface including a first conductive coating and a second surface including a second conductive coating; ii) a second substrate spaced from said first substrate, said second substrate having a first surface including a third conductive coating, said second surface of said first substrate and said first surface of said second substrate facing each other in spaced-apart relation to define a chamber therebetween; iii) an electrochromic medium contained in said chamber and in contact with said second and said third conductive coatings, said electrochromic medium having a luminous transmittance that varies upon application of an electrical potential through said electrochromic medium; iv) facilities for applying electrical current to said first conductive coating to heat said first conductive coating, thereby preventing fogging of said window assembly; and v) facilities for applying electrical current to said second and said third conductive coatings to establish said electrical potential through said electrochromic medium and vary said variable luminous transmittance of said electrochromic medium.
The present invention also provides an electrochromic aircraft window assembly comprising: a) an outboard pane assembly; b) an electrochromic pane assembly comprising first and second spaced substrates defining a chamber therebetween and an electrochromic medium contained in said chamber, said electrochromic medium having a luminous transmittance that varies upon application of an electrical potential through said electrochromic medium; and c) an intermediate pane assembly having anti-fogging properties, wherein said outboard pane assembly and said electrochromic pane assembly have facing surfaces and said intermediate pane assembly is interposed between and spaced from said outboard pane assembly and said electrochromic pane assembly, said intermediate pane assembly preventing fogging of said respective facing surfaces of said outboard pane assembly and said electrochromic pane assembly.
The present invention further provides an electrochromic aircraft window assembly comprising: a) an outboard pane assembly; b) a vibration dampening/sound absorbing pane assembly comprising a laminate comprising a base substrate, an adhesive interlayer deposited over a surface of said base substrate, a sound dampening material layer deposited over said adhesive interlayer and adhered to said base substrate by said adhesive layer, and a first conductive coating interposed between said adhesive layer and said base substrate; c) an electrochromic pane assembly comprising a first substrate having a second conductive coating on a surface thereof and a second substrate having a third conductive coating on a surface thereof, said first and said second substrates spaced from each other with said second and said third conductive coatings facing each other to define a chamber therebetween, said electrochromic pane assembly further comprising an electrochromic medium contained in said chamber, said electrochromic medium having a luminous transmittance that varies upon application of electrical current to said second and said third conductive coatings to establish an electrical potential through said electrochromic medium; and d) a spacer frame assembly for retaining said outboard pane assembly, said vibration dampening/sound absorbing pane assembly and said electrochromic pane assembly in spaced-apart generally parallel facing relationship with said vibration dampening/sound absorbing pane assembly positioned between said outboard pane assembly and said electrochromic pane assembly, said spacer frame assembly providing a first chamber between said outboard pane assembly and said vibration dampening/sound absorbing pane assembly and second chamber between said vibration dampening/sound absorbing pane assembly and said electrochromic pane assembly.
The present invention also provides an electrochromic aircraft window assembly comprising: a) an outboard pane assembly; and b) electrochromic pane assembly spaced from said outboard pane assembly and defining a chamber therebetween, said electrochromic pane assembly comprising: i) a first substrate having first and second surfaces; ii) second substrate having first and second surfaces, wherein said second surface of said first substrate is facing and spaced from said first surface of said second substrate, said first and second substrates forming a chamber of generally uniform thickness therebetween and further comprising a first conductive layer on said second surface of said first substrate and a second conductive layer on said first surface of said second substrate; iii) an electrochromic medium contained in said chamber and in contact with said conductive layers, said electrochromic medium having a luminous transmittance that varies upon application of an electrical potential through said electrochromic medium; iv) at least one additional assembly selected from a distortion reducing assembly, a fogging reducing assembly and a sound dampening assembly; and v) facilities for applying electrical current to said first and said second conductive layers to impress said electrical potential through said electrochromic medium and vary said luminous transmittance of said electrochromic medium.